Imaging of tissues and isolated cells is a critical tool for determining the biochemical and molecular mechanisms involved in phenotypic and functional changes in tissues, cells, and subcellular organelles induced by exposure to xenobiotics. Recent advances in imaging, biological chemistry, and molecular biology, have led to an escalation in imaging technologies and use in the biomedical sciences over the last several years. Development of fluorescent probes, green fluorescent protein (GFP), confocal and two-photon optics, and photoelectronic detectors, have allowed the visualization of single molecules, monitoring of molecular interactions in live cells, and enhanced ability to image complex tissues. The complexity, time, and cost required for developing state-of-the-art imaging technologies makes it unfeasible for individual investigators to independently obtain these important tools and approaches for biomedical research. Therefore, the need exists for an organized group of specialists with the expertise in imaging technologies to acquire the instrumentation, master the applications, and assist individual investigators in using the technology to answer specific research questions. The long-term goal of the Cell Imaging and Analysis Facility is to provide access to state-of-the-art instrumentation and expertise in flow cytometry and cell sorting, histopathology, and microscopy. Our objective is to develop fluorescence-based technologies to meet the current and future needs of Center investigators. Our rationale is that access to state-of-the-art fluorescence technologies will allow Center investigators to determine specific mechanisms of xenobiotic action at the cellular level. The motivated and interactive staff of the facility provides expertise in complementary areas of imaging and analysis. Dr. Kerkvliet and Ms. Oughton have over 40 years combined experience in flow cytometry with an outstanding record of research productivity. Dr. Greenwood and Ms. Fraley have recently setup the confocal and widefield microscopy systems, publishing studies resulting from the development of fluorescence recovery after photobleaching and fluorescence resonance energy transfer microscopy. Dr. Lohr is a certified Veterinary Pathologist with important collaborative interactions with Center investigators demonstrated by recent publications and Ms. Fischer has over 20 years of experience in histology, image analysis, and electron microscopy. Lastly, our collaboration with Molecular Probes/lnvitrogen, providing access to reagents and expertise, makes us especially well-positioned to accomplish our objective.